I pushed for usage based charging in my university as an alternate to the previous scheme of free bandwidth except for fining the top 20 users at £2/gig. They now charge by the amount charged per gig by the UK academic network (JANET) of ~15p (23c) and I think that's perfectly reasonable. Usage based charging is not a bad idea. In fact, it's pretty great for the majority of consumers. Why shouldn't people pay for what they use? Where it's bad is where there isn't appropriate competition to drive the price to the correct network cost, but monopolies are a problem for fixed rate plans, too.